Hot Film Mass Air Flow Sensor, Function

Hot Film Mass Air Flow Sensor, Function




9/1 Hot film sensor
9/5 Electronics housing
B2/5 Hot film MAF sensor
RH Heating resistor
RL Temperature resistance
RS Sensor resistance

The elecronics in the hot film mass air flow sensor controls the temperature of the heating resistor (RH) by means of a variable voltage so that its temperature is 160°C above the intake air temperature detected by the temperature resistor (RL). The temperature of the heating resistor (RH) is detected by the sensor resistor (RS). If a change in temperature occurs because of an increase or reduction in the air flow, the electronics (9/5) adjusts the voltage of the heating resistor (RH) until the temperature difference is again achieved. This control voltage is used by the engine control unit as a measure for the metered air mass.